Merge pull request #209 from cloudant/65-improve-error-handling-message

Additional error details appended to HTTPError exception

Author: emlaver

CHANGES.rst

@@ -15,6 +15,7 @@
   an ``adapter`` arg of a ``Replay429Adapter`` with the desired number of retries and initial backoff. To replicate
   the 2.0.0 behaviour use: ``adapter=Replay429Adapter(retries=10, initialBackoff=0.25)``. If ``retries`` or
   ``initialBackoff`` are not specified they will default to 3 retries and a 0.25 s initial backoff.
+- [IMPROVED] Additional error reason details appended to HTTP response message errors.
 - [FIX] ``415 Client Error: Unsupported Media Type`` when using keys with ``db.all_docs``.
 - [FIX] Allowed strings as well as lists for search ``group_sort`` arguments.
 

src/cloudant/_common_util.py

@@ -263,6 +263,20 @@ def get_docs(r_session, url, encoder=None, headers=None, **params):
     resp.raise_for_status()
     return resp
 
+#pylint: disable=unused-argument
+def append_response_error_content(response, **kwargs):
+    """
+    Provides a helper to add HTTP response error and reason messages.
+    """
+    try:
+        if response.status_code >= 400 and response.json():
+            reason = response.json().pop('reason', None)
+            error = response.json().pop('error', None)
+            response.reason += ' %s %s' % (error, reason)
+            return response
+    except ValueError:
+        return
+
 # Classes
 
 class _Code(str):

src/cloudant/client.py

@@ -25,7 +25,8 @@
 from .database import CloudantDatabase, CouchDatabase
 from .feed import Feed, InfiniteFeed
 from .error import CloudantException, CloudantArgumentError
-from ._common_util import USER_AGENT
+from ._common_util import USER_AGENT, append_response_error_content
+
 
 class CouchDB(dict):
     """
@@ -75,6 +76,9 @@ def connect(self):
             self.r_session.auth = (self._user, self._auth_token)
             self.session_login(self._user, self._auth_token)
         self._client_session = self.session()
+        # Utilize an event hook to append to the response message
+        # using :func:`~cloudant.common_util.append_response_error_content`
+        self.r_session.hooks['response'].append(append_response_error_content)
 
     def disconnect(self):
         """

tests/unit/document_tests.py

@@ -196,11 +196,13 @@ def test_create_existing_document(self):
         """
         doc = Document(self.db, 'julia006')
         doc.create()
-        try:
+        with self.assertRaises(requests.HTTPError) as cm:
             doc.create()
-            self.fail('Above statement should raise an Exception')
-        except requests.HTTPError as err:
-            self.assertEqual(err.response.status_code, 409)
+        err = cm.exception
+        self.assertEqual(
+            err.response.status_code,
+            409
+        )
 
     def test_fetch_document_without_docid(self):
         """
@@ -240,6 +242,28 @@ def test_fetch_existing_document_with_docid(self):
         new_doc.fetch()
         self.assertEqual(new_doc, doc)
 
+    def test_appended_error_message_using_save_with_invalid_key(self):
+        """
+        Test that saving a document with an invalid remote key will
+        throw an HTTPError with additional error details from util
+        method append_response_error_content.
+        """
+        # First create the document
+        doc = Document(self.db, 'julia006')
+        # Add an invalid key and try to save document
+        doc['_invalid_key'] = 'jules'
+        with self.assertRaises(requests.HTTPError) as cm:
+            doc.save()
+        err = cm.exception
+        self.assertEqual(
+            str(err.response.reason),
+            'Internal Server Error doc_validation Bad special document member: _invalid_key'
+        )
+        self.assertEqual(
+            err.response.status_code,
+            500
+        )
+
     def test_fetch_existing_document_with_docid_encoded_url(self):
         """
         Test fetching document content from an existing document where the